Modulating Electromagnetic Genes Through Bi-Phase High-Entropy Engineering Toward Temperature-Stable Ultra-Broadband Megahertz Electromagnetic Wave Absorption

Magnetic absorbers with high permeability have significant advantages in low-frequency and broadband electromagnetic wave (EMW) absorption. However, the insufficient magnetic loss and inherent high conductivity of existing magnetic absorbers limit the further expansion of EMW absorption bandwidth. Herein, the spinel (FeCoNiCrCu)₃O₄ high-entropy oxides (HEO) are successfully constructed on the surface of FeCoNiCr_0.4Cu_0.2 high-entropy alloys (HEA) through low-temperature oxygen bath treatment. On the one hand, HEO and HEA have different magnetocrystalline anisotropies, which is conducive to achieving continuous natural resonance to improve magnetic loss. On the other hand, HEO with low conductivity can serve as an impedance matching layer, achieving magneto-electric co-modulation. When the thickness is 5 mm, the minimum reflection loss (RL) value and absorption bandwidth (RL < - 5 dB) of bi-phase high-entropy composites (BPHEC) can reach - 12.8 dB and 633 MHz, respectively. The RCS reduction value of multilayer sample with impedance gradient characteristic can reach 18.34 dB m². In addition, the BPHEC also exhibits temperature-stable EMW absorption performance, high Curie temperature, and oxidation resistance. The absorption bandwidth maintains between 593 and 691 MHz from - 50 to 150 °C. This work offers a new and tunable strategy toward modulating the electromagnetic genes for temperature-stable ultra-broadband megahertz EMW absorption.